US1594022A - Furnace thermostat switch - Google Patents

Description

L E. SMITH JN w E. mm NN QN wN lNvENToR ESI/ruik um ATTORNEY July 27, 1926.

FURNACE THERMOSTAT `SWITCH Filed Sept. 5.

Patented July 27, 1926. y i

U'NITED'STATES PATENT OFFICE.

IBA EDWARD SMITH, F BTOCKTON, CALIFORNIA.

IURNACE THERHOBTAT BWITCE.

' Application med september s,.- iaas. semina. 55,0311.

- switch fundamentally comprised a plurality of mercury containing tubes, having contacts mounted at varying angles and arranged as a unit to bev rotated upon the expandin of the thermostatic element. I retain this fundamental construction but have provided, however, certain im ortant changes in the thermostatic means or operatin said switch contact unit. In t e previous switchthe initial movement of the switch tube unit which controlled the closing of the switch startin the sparkingand electric heating devices o the burner, was had by electrically heating the thermostatic element itself to a degree necessary to im art the desired rotation to the tube unit. his consumed considerable current and an appreciable time elapsed before such. rotation took lace.

The princi al o ject of my present invention there ore is to provide a more simple and quicker operating means for initially rotating the tube unit, so that less current is used and there is less delay between the initial turnin on of the current and ,the functioning o the burner.

I have also redesigned the arran ement' of the main thermostat relative to e switch .tube unit, so that much shorter len hs of 'l the expansible and nonexpansible e ements may be used, while at the same time. I arrange for ample movement of the member which controls the major rotation of said tube unit. 4

A further object of the invention is to produce a sim le and inexpensive device and yet one which will be exceedin ly effecsuch structure and relative `arrangement of,

tive for the signed. These objects I accomplish'by means of purpose for which itis departs as will fully appear by a lrusal of the following specification and claliiiis., .i l.

In the drawings similar characters of ref-` erence indicate corresponding .parts 'in the several views:

Fig. 1 is a side view of my improved type `4 extends upwardly, an el wardly inside the vand is of thermostat switch, showing the same as mounted Vin connection with a furnace.

Fig. 2 is a side view of the device detached, partly broken out and lin section with the parts in their normal or cold positions.

. Fig.- 3 is a top plan view of the devicebetter From the lower end and adjacent one side of said platea horizontal pipe 2 projects, having a bracket 3 by means of which these parts may be supported in a fixed osition. At the outer 'end of the pipe 2 anot er pipe ow 5 connecting the adjacent ends of both pipes. Another length ofhorizontal pi e 6 extends from beyond the upper end o the pipe 4, with an elbow 7 connecting the ad}acent ends of these` i s. f'

' A rigid rod 8 is mounted in the pipe 6 supported therefrom only at the outer end of t e latter. At its opposite end the rod 8 is supported from one arm of a bellcrank 9 which is mounted in the elbow 7. Another rod 10 is supported from the other arm of the bellcrank 9 and .extends downpi e 4 to a connection with one arm of abeilcrank 11 mounted in the elbow 5. The opposite end of the bellcrank 11 is connected to a rod 12 whichis mounted in the pipe 2 and projects through the same to a termination )ust inwardly of the plate 1.

The various rods are supported from the bell-cranks and pipe 6 in the following manner:

In the outer end of pipe 6 is a nut 6* having a needle point 6 on its inner end engaging a socket in the corresponding end of a shoulder or bushing 2 in which rod l2 is slidable, and a com ression spring 12l about said rod beyond t e shoulder and bearing thereagainst and against a collar 12h on the rod tends to retract the rod away from the inner face of the plate 1, and serves to hold all the needle oint bearings in firm engagement with eac other, re ardless of the expansion or contraction o the pipe 6.

The device is mounted in connection with a furnace box 13 in which an oil' burner is located, so that the pipe 2 enters the furnace at the ash box, the pipe 4 extends upwardly along the inside of the furnace, and the pipe 6 projects across the furnace above the burner. s

The pipe 6 is therefore located so as to be subjected to the direct heat of the burner,

the other pipes being heated to a much lesser4 de ree.

he ipe 6 and rod 8 form the maln thermostatic elements of my device. The pipe 6 is preferably made of nichrome steel--v anl element capable .of expanding under heat but offering considerable resistance to disintegration by reason of such heat. The rod 8 is preferably made of fused silicaan element of practically non-expansible nature. It will therefore be seen that if the pipe 6 expands relative tc the rod 8, relative movement between the bellcrank end of said rod 8 and the adjacent end of the pipe 6 will be had. This causes the turning of the adjacent bellcrank on its pivot, and conse uentlya longitudinal movement of the rdd 10; a turning of the bellcrank 1l; and a lon itudinal movement of the rod 12 will be ad in their respective enclosures. The parts are so arranged that when the pi e 6 is heated, the outer end of the rod 12 w1ll recede in the pipe 2.

Owing to the use of bellcranks whose arms maybe., designed to give any desired lever- ""age, the length of the elements 6 and 8,

and consequently? the amount of relative movement therebetween, may be very'short, and still provide for considerable movement of the free end of the rod 12. The pipes 2 and 4 and the corresponding rods are made of ordinary steel so that expansion and contraction, if any, will be the same throughout and will not affect the result.

Turnably supported from the plate 1 and disposed below the plane of the rod 12 and at right angles thereto is a horizontal shaft 14. A short arm 15 projects upwardly from said shaft and is bent at its upper end to extend toward and abut against the adjacent end of the rod 12.

A spring 16 about said shaft acts to hold the arm 15 in engagement with the rod 12 and to rotate said shaft when the rod recedes.

Brackets 17 project horizontally from the plate 1 adjacent the sides thereof a certain distance above the rod 12, in which brackets is turnably mounted a supporting structure having a plurality of switch-contact mem- These v'members are in the form of tubes 19, set at different angles relative to each other, and having contacts 20 projecting thereinto, certain ones of which contacts are lnormally immersed in mercury 21 sealed in the tubes but not filling the same.

This switch structure, its mounting, functioning and connection with the oil burner circuits, has been fully set forth in the copending a plication before mentioned, and therefore oes not need to be enlarged -upon here. It is believed to be sufficient to state that after a rotation of the structure 18 in a certain direction from a normal or cold position, the contacts will be broken or opened one after the other, by a change of level of the tubes, and a consequent flowing of the mercury away from the contacts.

vRotation is imparted to the structure 18 to effect such movement of the tubes in the following manner:

Projecting tangentially from and affixed to the shaft 14 adjacent one end thereof is an arm 22 to whose outer end is pivoted a rack 23 which engages a gear 24 fixed on' the corresponding end of the structure 18. The arm 22 is in itself a bimetal thermostat element, consisting of two superim osed metal strips A and B, the lower strip expanding to a greater extent than the other. A wire 25 is wound about the strips to form a coil 'heating element, and is electricall 'i insulated from said strips. When this coil is heated the arm 22 is heated also, causing the arm to assume a curved form from end to end with the upper face concave. Since the shaft 14 is stationary the arm 22 can' only move up at its other end, which will cause the rack 23 to move up and consequently impart rotation to the structure` 18. The wires 25 of the heating coil are connected in series with the wires of the contacts of that tube 19 whose contacts will be first broken with the rotation of the structure 18. These contacts are also in the circuit of the main starting switch of the system.

In operation therefore when such starting switch is closed, the arm 22 is heated, the structure 18 is rotated to break the first contact as above stated, which breaks the heater circuit. At the same time, as stated in the previous application, such rotation of the structure 18 has closed electric heating and sparking devices of the oil burner, and the latter is then set in operation. The heat from the burner immediately and directly affects the thermostat elements 6 and 8 so 14 will be rotated a distance enough lto compensate for the retracting tendency of the rack had with the cooling olf of the arm 22.

Thereafter with the further heatin of the main thermostat elements in the urnace, the arm 22 is rigid and inactive, and merely serves as an operating means for the rack 23 with the rotation of the shaft.

The arm 22 being small, the current and time necessary to cause the same to be heated and to function as above stated, are very small, and a quick starting of the burner into actual operation results from the use of this device.

, Owing to the use of agear on the switch of the invention as set forth herein.

While this specification sets forth in de` tail the present and preferred construction of the device, still in practice such' deviations from such detail may be resorted to as do not form a de arture from the spirit ofthe invention, as ened by the appended claims.

Having thus described my invention what I claim as new and useful and -desire to secure by Letters Patent is:

1. A thermostat switch including expansible and nonexpansible elements mounted together for relative longitudinal movement when subjected to the influence of heat, al

v shaft, means whereby said shaft will be rotated upon the expansion of said element, an arm projecting substantially radially from the shaft, a rotatable switch Contact structure whose axis of rotation is located in a plane parallel to but vertically spaced from said shaft, means whereby the contacts will be opened when said structure is rotated from a (predetermined osition, a gear fixed on sai structure axia ly thereof and a rack projecting from the outer end of the arm at an' angle thereto and engaging the gear, whereby the shaft when rotated will cause an arcuate movement of the arm and a consequent longitudinal movement of the rack and a rotation of the gear and switch structure.

2. A structure as in claim 1, in which said arm is of bimetal construction, and means is applied thereto for heating the same; said arm eing so arranged as to cause the same when heated, to movev the rack and rotate the gear and switch structure regardless of any movement of the shaft.

3. A thermostat switch including expansive and -nonexpansive elements mounted together for relative longitudinal movement when subjected to the influence of heat, a rotatable switch contactv structure mounted in connection with said elements, means whereby the contacts `will be opened when said structure is rotated to a certain extent from a predetermined osition, means between the elements and) the structure for causing the latter to be rotated when said elements are heated, and thermostatic means for enabling said structure to be rotated independent of heat applied to the said elements.

4. Operating means for a thermostat switch which includes a movable, member whose movement causes the contacts to be opened, comprising expansive and nonexpensive elements mounted together for rnlative longitudinal movement whenl subjected to the influence of heat, the expansible element being in the form of a tube of nichrome steel, and the nonex ansible element being in the form of a ro of fused silica disposed within the tube; said elements being operatively connected to the movable member of the switch to impart movement thereto with the relative movement between the elements.

5. A thermostat switch including expansive and nonexpa-nsi've elements mounted together for relative longitudinal movement when subjected to the influence of heat, a rotatable switch contact structure mounted in connection With said elements, means whereby the contacts will be opened .when said structure is rotated to a certain extent from a predetermined position, a relatively movable rod, means between the rod and the structure for causing the latter to be rotated when said elements are heated, and connections between` said rod and the elements for enabling the extenty of movement of the rod to be greater than the movement between the elements themselves.

6. A structure as in claim 5, in which said last named means comprises a pipe surrounding the rod, another y pipe extending at an an le to the first pipe, hollow connections etween the adjacent ends of the pipeand between the opposite end of the ast named pipe and the expansible element,

together for relative longitudinal movement y when subjected to the influence of heat, a shaft, means whereby said shaft will be rotated vupon the expansion of said element,

an arm projecting from the shaft', a rotatable switch-contact structure mounted in connection with the shaft, means whereby the contacts will be opened when said strueture is rotated to a certain extent from a predetermined position, means between the arm and structure for causing the latter to be rotated with a movement of the arm caused by the rotation of the shaft, and means provided in connection with the arm for causing the same to move to rotate the structure independent of any rotation of the shaft.

In testimony whereof I aix my signature.`

' IRA EDWARD SMITH.

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